JP3090194B2 - Mobile Host Multicast Communication Method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicast communication method for a mobile host, and more particularly to a multicast packet transfer control method for a mobile host moving in a network in which a plurality of sub-networks are interconnected.

[0002]

2. Description of the Related Art In a multicast communication in a network in which a plurality of sub-networks are interconnected,
In order to effectively use the multicast address and limit the hosts participating in the multicast group, the reach of the multicast packet is limited based on the physical network topology for each subnetwork.

[0003] The packet reach in multicast communication is called a scope (eg, Stephen Deerin).
g, "Multicast routing in a datagram internetwork",
Ph.D. Thesis, Stanford University, 1991). For example, in Internet Protocol version 6 (IPv6), this scope setting can be realized by embedding a scope field in a multicast address as shown in FIG. The scope field is defined, for example, as shown in FIG.
Hinden, S. Deering "IP Version 6 Addressing Archi
tecture ", Request for Comment 1884, RFC 1884, Dece
mber 1995).

On the other hand, there is a network that supports a mobile host that can move between sub-networks while performing communication (for example, Okanoue, Osawa, Goto, Komatsu, "Proposal of IP system for mobile terminal using double IP header", IEICE, IEICE, IN95-64, Vol.95, No.26
9, September 1995).

In this network, a node that assists a mobile host called an agent is arranged in a subnetwork supporting mobile hosts, and a special agent called a home agent is defined for each mobile host. Then, each mobile host always registers the current location information with the home agent. The location information of the mobile host is also registered in an agent (called a foreign agent) of the subnetwork that currently exists (locates). Each mobile host has an immutable identifier (home address) independent of its current location,
It is managed by the home agent using this identifier.

FIG. 25 shows such a network.
FIG. 25 shows that a mobile host 252 having a subnetwork 251 as a home network
254 is shown. In this case, the agent of the subnetwork 254 becomes the foreign agent 255, and receives the position information notification message 256 from the mobile host 252, and registers the position information. Also, the home agent 257 receives the location information notification message 258 from the mobile host 252 and registers the location information.

Now, a network as shown in FIG.
Consider adopting the above-described multicast communication.
In this case, in a network as shown in FIG. 25, the moving range of the mobile host cannot be determined in advance, so that the multicast communication for limiting the reach of the multicast packet cannot be directly applied to this network. That is, in the conventional multicast communication, the mobile host cannot join the multicast group.

[0008] As one conventional method for joining a mobile host to a multicast group, a logical channel called a bidirectional tunnel is prepared between a home agent of each mobile host and each mobile host, and multicast packets are transmitted to a multicast channel. There is a method of encapsulating it in a cast packet and transferring it (transfer participation method).

In this method, as shown in FIG. 26, a home agent 265 of a home network 264 included in a scope 263 receives a multicast packet 262 transmitted from a source 261 of a multicast group. Then, the home agent 265 transmits the encapsulated multicast packet (unicast packet), and the mobile host 266 receives the unicast packet via the bidirectional tunnel 267.
Thus, the mobile host 266 has
65 can be used as a relay point to join the multicast group. When transmitting the multicast packet from the mobile host 266, the encapsulated multicast packet is transmitted to the home agent 265 through the bidirectional tunnel 267, and the home agent 265 removes the encapsulation and transfers the packet.

As another conventional method for joining a mobile host to a multicast group, there is a method (direct joining method) in which a mobile host directly transmits and receives a multicast packet in a destination in the same manner as a fixed host. .

In this method, as shown in FIG. 27, even when the home network 272 is not included in the scope 271, the mobile host 273 that has moved from the home network 272 into the scope 271 is directly sent to the multicast. The multicast packet 275 from the transmission source 274 of the group is received. Mobile host 27
3 is also directly transmitted.

The above two methods for joining a mobile host to a multicast group are described, for example, in Charles Peal.
rkins, "IP Mobility Support", Request for Comment:
2002, RFC2002, October 1996.

[0013]

In the multicast communication in consideration of the mobile host, the nature of the group is as follows: Group 1: If the mobile host belongs to the management organization that manages a certain subnetwork, the currently connected subnetwork A group that is a member of a group regardless of the administrative organization that manages the network. Group 2: A group in which all mobile hosts that are currently directly connected to a subnetwork are members, regardless of the administrative organization to which the mobile host belongs. Conceivable.

However, in the conventional transfer joining method,
If the home agent is not in scope,
Even if the mobile host is located within the scope, it cannot receive packets, so that there is a problem that group 2 cannot be realized.

In this method, if a home agent exists in the scope, the packet is transmitted irrespective of the position of the mobile host, so that the destination cannot be limited to the scope. There is a problem that group 2 cannot be realized.

On the other hand, in the conventional direct participation method, even if the home agent is within the scope, the packet cannot be received if the mobile host moves out of the scope, so that the group 1 cannot be realized. There is a point.

In addition, this method has a problem in that group 1 cannot be realized because a mobile host of a management organization that has not been permitted to participate in a group cannot reject participation when it moves into the scope.

An object of the present invention is to provide a multicast communication method for a mobile host, which can allow a mobile host to join a group according to the characteristics of the multicast group.

[0019]

According to the present invention, there is provided a multicast communication method for a mobile host, wherein one of the plurality of hosts transmits a call on a network interconnecting a plurality of sub-networks each connected to a plurality of hosts. A multicast that is a source host, selects one or more sub-networks from the plurality of sub-networks to form a multicast group, and transmits information to all other hosts connected to the sub-network belonging to the multicast group A mobile host multicast communication method, comprising: connecting a mobile host that can be connected to any of the plurality of sub-networks and managed by a node called a home agent disposed in any of the plurality of sub-networks to communication. ,
a) the source host broadcasts predetermined information on the multicast group to the multicast group as group characteristic information, and b) the home agent transfers the received group characteristic information to the mobile host. C) the mobile host receives the group characteristic information transmitted from the source host or the group characteristic information transferred from the home agent, and based on the predetermined information, It is characterized in that it is determined whether or not to participate.

Further, the multicast communication system of the present invention has a plurality of sub-networks connected to each other, and a plurality of hosts connected to the plurality of sub-networks. As a source host, one or more subnetworks are selected from the plurality of subnetworks to form a multicast group, and information is transmitted to all other hosts connected to the subnetworks belonging to the multicast group. A) a mobile host connectable to any of the plurality of sub-networks; and b) a home agent located in any of the plurality of sub-networks and managing the mobile host. Along with a called node,
c) each of the plurality of hosts is provided with a notifying means for notifying the multicast group of predetermined information on the multicast group as group characteristic information when forming the multicast group; and d. E) transfer means for transferring the received group characteristic information to the home agent to the mobile host; e) transfer of the group characteristic information transmitted from the source host or the home agent to the mobile host. And receiving means for determining whether or not to participate in the multicast group based on the predetermined information.

Further, in the multicast communication method of the mobile host according to the present invention, the mobile communication system comprises a plurality of interconnected sub-networks, and identifies the host itself without depending on the sub-network which is directly connected at present. A plurality of mobile hosts having an identifier (location identifier) based on the sub-network currently connected directly to the sub-networks, and capable of moving between the sub-networks while performing communication, A node called a home agent that manages each of the mobile hosts is arranged in the subnetwork defined by the logical address, is directly connected to the subnetwork, and has only an identifier (fixed identifier) dependent on the subnetwork. If there are multiple fixed hosts that do not move, In the multicast communication method of the mobile host in the network performing the port communication, the mobile or fixed host forming the multicast group includes: a) at least joining the multicast group from the plurality of interconnected sub-networks; A subnetwork defined by the theoretical identifier of the mobile host and a subnetwork defined by the fixed identifier of the fixed host are selected as the subnetwork group 1; b) information on the multicast group for the subnetwork group 1 As the group characteristic information, and c) the home agent existing in the sub-network group 1 is based on the group characteristic information. And determines whether or not to participate in the loop, d) based on said group characteristic information, the mobile hosts existing in the subnetwork group of 1 to decide whether to participate in the group.

The group characteristic information of the present invention includes: a) a transfer permission / prohibition attribute indicating whether or not to permit the transfer of the communication within the multicast group to the subnetwork other than the subnetwork group 1; and b) the multicast. The host that is permitted to participate in the group is a member restriction presence / absence attribute indicating whether or not to restrict to the transport host and the fixed host managed by the organization that manages the subnetwork of the subnetwork group 1, and c) the multicast. And a group identifier for identifying the group.

The home agent of the present invention: a) upon receiving the group characteristic information of the multicast group, a group characteristic storage means for storing the transfer permission / inhibition attribute, the member restriction presence / absence attribute, and the group identification of the multicast group. And b) selecting the mobile host managed by the home agent when the stored transferability attribute allows the communication in the multicast group to be transferred to the subnetwork other than the subnetwork group 1. Means for transferring the group characteristic information of the multicast group to the selected mobile host.

[0024] The home agent of the present invention receives the group characteristic information of the multicast group,
If the transferability attribute of the multicast group allows the communication within the multicast group to be transferred to the sub-networks other than the sub-network group 1, a) for the mobile host managed by the home agent: Means for transmitting a home agent group characteristic information inquiry message for inquiring whether or not the group characteristic information of the multicast group has been received; and b) the mobile host transmits the home agent group characteristic information inquiry message in response to the home agent group characteristic information inquiry message. If the property information has already been received, a mobile host group property information received message is received. If the mobile host has not received the group property information, a mobile host group property information not received message is received. hand C) upon receiving the mobile host group characteristic information received message, does not transfer the group characteristic information to the mobile host that transmitted the mobile host group characteristic information received message; Means for transferring the group characteristic information as transfer group characteristic information from the home agent to the mobile host that has transmitted the unreceived message.

In the transfer group characteristic information of the home agent according to the present invention, a transfer flag indicating that the home agent has transferred is inserted into the group characteristic information.

The home agent group characteristic information inquiry message of the present invention includes a) the group identifier of the multicast group to be inquired.

The mobile host group characteristic information received message of the present invention includes: a) the group identifier of the queried multicast group; and b) the logic of the mobile host that transmitted the mobile host group characteristic information received message. And c) a flag indicating that the group identifier has been received.

The mobile host group characteristic information not received message of the present invention includes: a) the group identifier of the queried multicast group; and b) the sub-host of the mobile host that transmitted the mobile host group characteristic information received message. An identifier based on the sub-network managed by the managing organization independent of the network; c)
The flag includes a flag indicating that the group identifier has not been received.

The mobile host of the present invention receives the group characteristic information of the multicast group and the transfer group characteristic information from the home agent of the multicast group, and the mobile host can a) directly join the multicast group. Means for judging that the group can be directly joined; b) means for judging that the group is a transfer joinable group that can join the multicast group by the transfer of the home agent; and c) participation impossible that cannot join the multicast group. Means for determining a group.

[0030] The mobile host of the present invention comprises: a) means for distinguishing between the group characteristic information of the multicast group and transfer group characteristic information from the home agent of the multicast group; b) determining whether the multicast group is the directly joinable group; c) determining whether the multicast group is the non-joinable group if the multicast group is not the directly joinable group; If the group is not the non-participating group, check the member restriction presence / absence attribute of the multicast group; if there is no member restriction, holding the multicast group as the directly participating group; d) the member Restriction existence attribute has member restriction In the case of the means for transmitting the mobile host group characteristics received inquiry message inquiring whether to receive the group characteristic information of the multicast group to the home agent,
e) a home agent received message indicating that the home agent has received the group characteristic information, obtained from the home agent in response to the mobile host group characteristic reception inquiry message, or Means for receiving a home agent unreceived message indicating that information has not been received; and f) when the home agent received message is received,
Means for holding the multicast group as the directly joinable group; and g) means for holding the multicast group as the non-joinable group when the home agent non-received message is received.

The mobile host according to the present invention comprises: a) means for distinguishing said group characteristic information of said multicast group and transfer group characteristic information from said home agent of said multicast group, wherein said transfer group characteristic from said home agent is included. Upon receiving the information, b)
Determining whether the multicast group is the directly joinable group; c) if the multicast group is not the directly joinable group, determining whether the multicast group is a non-joinable group; Is not the non-participating group, the multicast group holds the transferable group. If the multicast group is the non-participating group, the multicast group is not the non-participating group. D) group property information indicating that the transfer of the group property information to the home agent is unnecessary when the multicast group is the directly joinable group. Send a forwarding unnecessary message.

[0032] The mobile host group characteristic reception inquiry message of the present invention comprises: a) the identifier of the multicast group making the inquiry; and b) the logical identifier of the mobile host transmitting the mobile host group characteristic reception inquiry message. Contains.

The home agent non-received message of the present invention includes: a) the group identifier for identifying the multicast group queried by the mobile host group characteristic reception inquiry message; and b) the home agent is the group of the multicast group. It includes a flag indicating that the characteristic information has not been received.

[0034] The home agent received message of the present invention includes: a) the group identifier for identifying the multicast group queried by the mobile host group characteristic reception inquiry message; and b) the group of the multicast group. It includes a flag indicating that the characteristic information is being received.

The group characteristic information transfer unnecessary message according to the present invention includes: a) the identifier of the multicast group which does not require the transfer of the group characteristic information; and b) the mobile host transmitting the group characteristic information transfer unnecessary message. Logical identification.

When the home agent of the present invention receives the mobile host group characteristic information inquiry message of the present invention from the mobile host of the present invention, a) the mobile host determines that the group identifier included in the group characteristic information inquiry message is the group. Detecting whether or not it is registered in the characteristic storage means, b) sending the home agent received message to the mobile host if registered, and sending the home agent not received message to the mobile host if not registered It is characterized by doing.

When the home agent of the present invention receives the group characteristic information transfer unnecessary message of the present invention from the mobile host of the present invention, a) the multicast identified by the group identifier included in the group characteristic information transfer unnecessary message Transferring the group characteristic information of the group to the mobile host is stopped.

When the mobile host of the present invention receives the home agent group characteristic information inquiry message of the present invention, a) extracts the group identifier contained in the home agent characteristic information inquiry message;
b) if the group identifier is registered as the direct participation group, send the mobile host group characteristic information received message to the home agent; c) the group identifier is registered as the direct participation group. If not, the mobile host group characteristic information not received message is transmitted to the home agent.

[0039]

According to the present invention, as an attribute indicating the property of a multicast group, an attribute (transfer) indicating whether or not to permit the host constituting the multicast group to extend the scope defined in the group and transfer the multicast group. Organizations that are allowed to participate as members at least with group attribute information that has an attribute (member restriction existence attribute) that indicates whether or not participation of hosts belonging to organizations other than the organization that manages the subnetwork restricted by the scope is permitted. To notify within the sub-network managed by.

The home agent transfers all information indicating the properties of the group to which the transfer is permitted, based on the transfer permission attribute. The mobile host that has received the transfer information determines whether or not to participate, and if so, participates by the transfer participation method.

On the other hand, the mobile host that directly receives the group attribute information joins the group by the direct participation method when the member restriction presence / absence attribute does not indicate the member restriction. If there is a member restriction, an inquiry is made to the home agent that has group attribute information about the same group. If the home agent has the group attribute information, the managing organization is within the scope, and the mobile host joins the group by the direct participation method.

As described above, even a mobile host existing outside the scope can join the group via the home agent existing within the scope.
Also, when it is within the scope, you can directly join the group.

On the other hand, a host constituting a multicast group can disallow a mobile host existing outside the scope from joining the group. In addition, even if a mobile host exists within the scope, if the home agent does not exist within the scope, participation in the group can be prohibited.

[0044]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a network to which the multicast communication method of the present invention is applied. This network includes a backbone network 100 and a subnetwork 10
1, 102, 103, and 104. Then, the sub-networks 101, 102, 103, and 1
04 is connected to the backbone network 100 via routers 105, 106, 107 and 108, respectively. Note that these networks are managed by different management organizations.

This network has a plurality of mobile hosts 110, 111, 112 and 113. The mobile hosts 110 and 111 are managed by the home agent 120 belonging to the subnetwork 101, and the mobile hosts 112 and 113 are managed by the home agent 121 belonging to the subnetwork 103. At present, the mobile hosts 110 and 113 Within the network 102, mobile hosts 111 and 112 have moved (located) within the sub-network 104.

Each mobile host has an address (logical address) representing the host irrespective of the current position, and an address (position address) depending on the current position. These addresses are reported to the home agent managing each mobile host.

The host 130 forms a multicast group including at least hosts belonging to the organization that manages the sub-networks 101 and 102, and forms a scope 140 of the group.

In the above situation, each mobile host can be classified into the following four connection modes. Connection mode 1: The management organization (home network) to which the user belongs and the current destination are both within the scope 140. The mobile host 110 is classified into this connection mode 1. Connection mode 2: The management organization to which the user belongs is within the scope 140, but the current destination is outside the scope. The mobile host 111 is classified into this connection mode 2. ● Connection type 3: The management organization to which the user belongs and the current destination are
Both exist outside the scope 140. Mobile host 1
No. 12 is classified into this connection mode 3. Connection mode 4: The management organization to which the user belongs is outside the scope 140, but the current destination is within the scope. The mobile host 113 is classified into this connection mode 4.

On the other hand, the multicast group enables / disables the transfer of the multicast packet from the home agent within the scope to the mobile host outside the scope (allows the mobile host outside the scope to join the group /
Depending on whether or not the out-of-scope transfer permission attribute and the management organization to which the mobile host located in the scope belongs are in the scope, whether the mobile host is allowed to participate in the group is determined as permission / non-permission. Are defined, and the combination is classified into the following four types. -Type 1: Out-of-scope transfer is possible, with member restrictions.・ Type 2: Out-of-scope transfer possible, no member restrictions.・ Type 3: Out-of-scope transfer is not possible and members are restricted. -Type 4: Out-of-scope transfer is not possible, and there is no member restriction.

Therefore, depending on the combination of the connection form of the mobile host and the type of the multicast group, the form of participation of each mobile host in the multicast group is as follows. ● Connection type 1 ・ Type 1: Since both the management organization and the destination are within the scope, they participate in the direct participation method. -Type 2: Since both the management organization to which the user belongs and the destination are within the scope, they participate in the direct participation method. -Type 3: Since both the management organization to which the user belongs and the destination are within the scope, they participate in the direct participation method. -Type 4: Since both the management organization to which the user belongs and the destination are within the scope, they participate in the direct participation method. ● Connection form 2 ・ Type 1: Since the management organization to which the user belongs is within the scope, he / she has the participation qualification even if the members are restricted. However, since the destination is out of the scope, the user joins the group by the transfer participation method via the home agent.・ Type 2: Since the management organization to which the user belongs is within the scope, he / she has the participation qualification. However, since the destination is out of the scope, the user joins the group by the transfer participation method via the home agent. Type 3: The destination is out of the scope and the transfer to outside the scope is not permitted, so that the user cannot join the group. Type 4: The destination is out of the scope, and the transfer to outside the scope is not permitted, so that the user cannot join the group. ● Connection form 3 ・ Type 1: Since the management organization to which the user belongs and the transfer destination are both outside the scope, the existence of the group cannot be known. Therefore, they cannot join the group. Type 2: Since the management organization to which the user belongs and the transfer destination are both outside the scope, the existence of the group cannot be known. Therefore, they cannot join the group. Type 3: Since the management organization to which the user belongs and the transfer destination are both outside the scope, the existence of the group cannot be known. Therefore, they cannot join the group. Type 4: Since the management organization to which the user belongs and the transfer destination are both out of scope, the existence of the group cannot be known. Therefore, they cannot join the group. ● Connection type 4 ・ Type 1: The management organization to which the user belongs belongs out of the scope,
Due to member restrictions, you cannot join the group. -Type 2: Since the destination is within the scope and there is no member restriction, even if the management organization to which the user belongs is outside the scope, he / she can join the group by the direct participation method.・ Type 3: The management organization to which the user belongs is outside the scope,
Due to member restrictions, you cannot join the group. -Type 4: Since the destination is within the scope and there is no member restriction, even if the management organization to which it belongs is outside the scope, it can participate in the group by the direct participation method.

FIG. 2 shows the form in which the mobile host participates in the group. In the present invention, such a form of joining a mobile host to a group is realized.

Hereinafter, a multicast communication method for realizing the participation mode of FIG. 2 will be specifically described.

First, the host (originator) holding the multicast group determines the scope of the group to be held, the out-of-scope transfer permission attribute indicating the attribute of the group, and the member restriction presence / absence attribute. The scope is defined so that the originator includes all subnetworks that manage the hosts that are allowed to join the group as members. As this kind of scope, for example, a definition as shown in FIG. 24 can be used. The attribute limits the participating members and transfer destinations according to the nature of the group held by the originator.

The originator reports information (multicast group information) such as an out-of-scope transfer permission attribute, a member restriction presence / absence attribute, a scope, a unique group identifier, and the like defined for the group to be held within the same scope as the group to be held. I do. The notification of this information is, for example,
Mark Handley, "SAP: Session Announcement Protocol",
Internet engineering draft, work in progress, session announcement protocol (SA
P). As an example of the multicast group information, for example, Mark Handley, "SDP: Sessi
onDescriptionProtocol ", internet engineeringdraft,
work in progress.

FIG. 3 shows the SAP message format. The SAP message in FIG.
The multicast group information description unit 303 includes a DP header 301, an SAP header 302, and a multicast group information description unit 303. The multicast group information description unit 303 includes at least a group identifier, an out-of-scope transfer enable / disable attribute, a member restriction presence / absence attribute, and a group existence time. I have.

Next, the operation of the home agent receiving the SAP message as shown in FIG. 3 will be described.

The home agent manages a set of a logical address and a location address of a mobile host managed by the home agent. For example, the home agent 120 that manages the mobile hosts 110 and 111 has a mobile host management table as shown in FIG. Here, FIG.
10 shows a case where the logical address and the position address of the logical host 1 are the logical address 1 and the position address 1, respectively, and the logical address and the position address of the mobile host 111 are the logical address 2 and the position address 2 respectively.

The home agent refers to the group identifier, the out-of-scope transfer permission / inhibition attribute, and the member restriction presence / absence attribute included in the SAP message as group characteristics, and manages them using a group characteristic table as shown in FIG. In FIG. 5, the home agent receives the SAP messages of four groups represented by the group identifiers 1 to 4, and the (out-of-scope transfer permission / inhibition attribute, member restriction presence / absence attribute) of each message is
(Yes, Yes), (No, Yes), (Yes, No), and (No, No)
Is shown.

Further, the home agent is configured as shown in FIG.
Has a group characteristic transfer table as shown in FIG. This table contains information on whether or not it is necessary to transfer the group characteristics of a group having an attribute of “out-of-scope transfer allowed” among the SAP messages received by the home agent to a mobile host managed by the home agent. keeping. That is, FIG. 6 is based on the group property transfer table held by the home agent having the mobile host management table of FIG. 4 and the group property table of FIG. Yes, there is no need for transfer to the mobile host 111.

Next, the operation when the home agent receives the SAP message will be described with reference to FIG.

First, the home agent performs step S
When an SAP message (group characteristic information) is received in 701, the group characteristic table is searched in step S702, and it is determined whether or not the group identifier included in the message has been registered in the group characteristic table.

If the group identifier of the received SAP message is already registered in the group characteristic table, the home agent proceeds to step S703.
Then, the out-of-scope transferability attribute of the SAP message is checked, and if the out-of-scope transfer is not possible, step S704.
Then, the received SAP message is discarded. Conversely, SA
If the P message can be transferred, step S705
Then, based on the information in the group characteristic transfer table, the data is transferred to the mobile host to be transferred. This SAP message transfer is performed in a packet format as shown in FIG. The packet format shown in FIG. 8 shows an example of a transfer message from the home agent 120 to the mobile host 111. That is, the home agent 120
Encapsulates the received SAP message (see FIG. 3) by adding an IP header 800 with the destination set to the location address of the mobile host 111 (position address 2) and the source address set to the address of the home agent 120. At the same time, information (transfer flag) indicating transfer from the home agent 120 is added to the multicast group information description unit 303 and transferred.

On the other hand, in step S702, the received SA
When determining that the P message has not been registered, the home agent registers the group identifier, the out-of-scope transfer permission / prohibition attribute, and the member restriction presence / absence attribute in the group property table in step S706. And
In step S707, it is determined whether the SAP message can be transferred based on the out-of-scope transferability attribute. If the SAP message cannot be transferred, the SAP message is discarded in step S704. vice versa,
If the SAP message can be transferred, step S70
At 8, the group identifier is registered in the group characteristic transfer table. At this time, for the registered group identifier, transfer necessity is set as information (initial value) of transfer necessity / unnecessity to each mobile host.

Subsequently, in step S709, the home agent determines whether or not the home agent has already received the SAP message including the group identifier registered earlier, to the mobile host managed by itself (more precisely, as described later, A message (home agent group identifier inquiry message) for inquiring about whether or not it is registered in the directly joinable group table is transmitted. This home agent group identifier inquiry message includes the group identifier of the group making the inquiry.

Each mobile host that has received the home agent group identifier inquiry message responds with a message indicating reception (mobile host received message) or a message indicating non-reception (mobile host not received message). Send. The mobile host received message includes a logical address of the mobile host, a group identifier, a flag indicating that the mobile host has been received,
The mobile host non-received message includes a logical address of the mobile host, a group identifier, and a flag indicating non-reception.

The home agent receives the response message from each mobile host, and determines that the received message is a mobile host received message, in step S71.
If the determination is 0, in step S711, the group characteristic transfer table is updated for the mobile host that has transmitted the message, so that transfer is unnecessary. Step S
If it is determined at 710 that the received response message is a mobile host unreceived message, the group characteristic transfer table for the mobile host that transmitted the message is not updated. That is, in step S712, the home agent keeps transferring the group characteristic transfer table for the mobile host that has transmitted the mobile host non-received message. And the SAP received earlier
Encapsulate the message and forward it to the mobile host.

FIG. 9 shows an example of the message exchange between steps S709 and S710 between the home agent and the mobile host. The example of FIG. 9 shows a case where the home agent manages the mobile hosts 1 and 2 and transmits a home agent group identification inquiry message for the multicast group identified by the group identifier A. At this time, the mobile host 1
Indicates that the group characteristic information identified by the group identifier A has been received (the group identifier A has been registered in the directly joinable group table), and the mobile host 2 has not received the information (the group identifier A has been registered in the directly joinable group table). Unregistered).

Next, the operation when the mobile host receives the SAP message will be described with reference to FIGS.

The mobile host has a directly participating group table as shown in FIG. 10, a non-participating group table as shown in FIG. 11, and a transfer participating group table as shown in FIG. In each of these tables, the group identifier of the corresponding group is registered. That is, the mobile host holding the tables shown in FIGS. 10 to 12 joins the groups whose group identifiers are groups 1 and 2 to the groups whose group identifiers are groups 5 and 6 by the direct participation method. Participation is permitted by the transfer participation method, but participation in groups having group identifiers of groups 3 and 4 is not permitted.

The mobile host receives two types of SAP messages. One is transmitted directly from the originator (see FIG. 3), and the other is transmitted from the home agent (see FIG. 8). Therefore, the mobile host performs step S as shown in FIG.
It is determined in step S1302 whether the SAP message (group characteristic information) received in 1301 is directly transmitted from the originator or transferred from the home agent. This determination can be realized by referring to the transfer flag of the multicast group information description section in the received SAP message.

If the received SAP message is a message transmitted from the originator, step S1303
Then, it is determined whether or not the group identifier is registered in the directly joinable group table. If it is registered, in step S1304, the received S
Discard the AP message. If not registered, it is determined in step S1305 whether the group identifier is registered in the non-participation group table. If the group identifier is registered in the non-participation group table, in step S1304, the received SAP message is discarded.

If it is determined in step S1305 that the group identifier is not registered in the non-participation group table, in step S1306, a check is made of the member restriction presence / absence attribute included in the received SAP message. As a result, if it is determined that there is no member restriction, the group identifier is registered in the directly joinable group table in step S1307. On the other hand, if there is a member restriction, in step S1308, it is determined whether or not the home agent managing itself has received an SAP message having the group identifier (as described later, the group identifier indicates the group Inquiry of whether or not it is registered in the characteristic table) (transmission of mobile host group identifier inquiry message). This mobile host group identifier inquiry message includes the group identifier to be inquired and the logical address of the mobile host.

Upon receiving the mobile host group identifier inquiry message, the home agent sends a response message indicating whether the SAP message having the inquired group identifier has already been received.

The mobile host determines that the response message from the home agent has already received the SAP message having the inquired group identifier (the group identifier has been registered in the group characteristic table) (the home agent has received the SAP message). message)
If it is determined in step S1309 that
In step S1307, the group identifier is registered in the directly joinable group table. Conversely, it is assumed that the response message from the home agent is a message that the SAP message having the inquired group identifier is not received (the group identifier is not registered in the group characteristic table) (home agent non-received message). If it is determined in step S1309, the group identifier is registered in the non-participation group table in step S1310. In addition, the home agent received message includes the group identifier inquired and a flag indicating that reception has been completed,
The home agent non-received message includes a group identifier for which an inquiry has been made and a flag indicating non-received.

FIG. 14 shows the exchange between each mobile host and the home agent between steps S1308 and S1309. FIG. 14 shows that mobile hosts 1 and 2 managed by the same home agent receive SAP messages (group characteristic information) of a multicast group identified by group identifiers A and B for their home agents, respectively. Shows the case where it is inquired whether or not there is. In this case, the home agent has received the group characteristic information of the group identifier A,
Since the group characteristic information of the group identifier B has not been received, the home agent received message is transmitted to the mobile host 1, and the home agent non-received message is transmitted to the mobile host 2.

Next, the case where the mobile host receives the SAP message transferred from the home agent will be described.

If the mobile host determines in step S1302 that the received SAP message has been transferred from the home agent, it proceeds to step S13.
At 11, it is determined whether the group identifier is registered in the directly joinable group table.

If the group identifier is registered in the directly joinable group table, the mobile host determines in step S1312 that the home agent does not need to transfer the group property information (group property information transfer unnecessary). Message). The group characteristic information transfer unnecessary message includes a target group identifier, a logical address of the mobile host, and a flag indicating transfer unnecessary. This message exchange is shown in FIG. FIG. 15 shows a case where the mobile host 1 transmits a group characteristic information transfer unnecessary message to the home agent, assuming that transfer of the group characteristic information of the multicast group identified by the group identifier A is unnecessary.

If it is determined in step S1311 that the group identifier is not registered in the directly joinable group table, the mobile host proceeds to step S1313.
It is checked whether the group identifier is registered in the non-participation group table.

If the group identifier is registered in the non-participating group table, the mobile host deletes the group identifier from the non-participating group table in step S1314, and transfers the group identifier to the non-participating group table in step S1315. Register in the group table. If the group identifier is not registered in the non-participation group table, the process immediately proceeds to step S131.
At 5, the group identifier is registered in the transfer participation possible group table.

As can be seen from the above description, the home agent receives the mobile host received message, the mobile host not received message, and the group characteristic information transfer unnecessary message from the mobile host in addition to the SAP message from the originator. I do. When receiving these messages, the home agent updates the group characteristic transfer table (see FIG. 6) as follows.

That is, when the home agent receives the mobile host non-received message from the mobile host,
As shown in (1), the SAP message related to the group of the group identifier included in the message is updated to be transferred to the source mobile host. When the home agent receives the mobile host received message, as shown in FIG. 17, the home agent updates the SAP message related to the group of the group identifier included in the message so that the SAP message is not transferred to the transmission source mobile host. Furthermore, when the home agent receives the group characteristic information transfer unnecessary message, as shown in FIG. 18, the home agent updates the SAP message related to the group of the group identifier included in the message so as not to transfer the SAP message to the transmission source mobile host.

The home agent receives a mobile host group identifier inquiry message from the mobile host. In this case, the home agent is as shown in FIG.
As shown in (1), the group characteristic table (see FIG. 5) is searched to determine whether the group identifier included in the message is registered. Then, if registered, a home agent registered message is transmitted to the transmission source mobile host. If not registered, a home agent non-received message is transmitted to the transmission source mobile host.

On the other hand, in addition to the SAP message, the mobile host receives a home agent group identifier inquiry message, a home agent received message, and a home agent not received message.

When the mobile host receives the home agent group identifier inquiry message, as shown in FIG. 20, it checks whether or not the group identifier included in the message is registered in the directly joinable group table. Then, the mobile host, when the group identifier is registered in the directly joinable group table, the mobile host received message, if not registered, the mobile host not received message,
Sent to home agent.

When the mobile host receives the home agent received message, as shown in FIG. 21, the mobile host registers the group identifier included in the message in the directly joinable group table. When the mobile host receives the home agent non-received message, as shown in FIG. 22, the mobile host registers the group identifier included in the message in the non-participation group table.

The procedure described above is introduced into the mobile host and the home agent, and the mobile host can directly participate in the group table (see FIG. 10), transfer participation group table (see FIG. 12), and non-participation group table. Based on (see FIG. 11), the home agent participates in the communication of the group identified by the group identifier based on the group characteristic transfer table (see FIG. 6), thereby realizing the communication mode shown in FIG. can do.

The group identifier registered in all the tables used by the mobile host and the home agent is immediately deleted when the group lifetime included in the group characteristic information identified by the identifier elapses. . When the mobile host moves and acquires a new location address, all group identifiers registered in all tables used by the mobile host are deleted. Furthermore, the home agent, which has been notified of the movement of the mobile host, changes all the transfer necessity / unnecessary information relating to the mobile host in the group characteristic information transfer table to transfer necessity.

[0090]

According to the present invention, a mobile host can also use a direct participation method and an indirect participation method appropriately without contradicting the scope limitation defined for a multicast group to join a multicast group having a qualification to participate. Will be able to participate.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of a network to which a multicast communication method of the present invention is applied.

FIG. 2 is a diagram showing a form in which a mobile host participates in a multicast group.

FIG. 3 is a diagram showing an SAP message format.

FIG. 4 is a diagram for explaining a mobile host management table of a home agent.

FIG. 5 is a diagram for explaining a group characteristic table of a home agent.

FIG. 6 is a diagram illustrating a group characteristic transfer table of a home agent.

FIG. 7 is a flowchart showing an operation when a home agent receives an SAP message.

FIG. 8 is a diagram showing a packet format transferred from a home agent to a mobile host.

FIG. 9 is a diagram for explaining message exchange between a home agent and a mobile host.

FIG. 10 is a diagram illustrating a directly joinable group table of a mobile host.

FIG. 11 is a diagram illustrating a non-participation group table included in a mobile host.

FIG. 12 is a diagram for explaining a transfer participating group table included in a mobile host.

FIG. 13 is a flowchart showing an operation when the mobile host receives an SAP message.

FIG. 14 is a diagram for explaining message exchange between a mobile host and a home agent.

FIG. 15 is a diagram for explaining exchange of messages between a mobile host and a home agent.

FIG. 16 is a flowchart showing an operation when a home agent receives a mobile host non-received message from a mobile host.

FIG. 17 is a flowchart showing an operation when the home agent receives a mobile host received message from the mobile host.

FIG. 18 is a flowchart illustrating an operation when a home agent receives a group characteristic information transfer unnecessary message from a mobile host.

FIG. 19 is a flowchart showing an operation when a home agent receives a mobile host group identifier inquiry message from a mobile host.

FIG. 20 is a flowchart showing an operation when the mobile host receives a home agent group identifier inquiry message.

FIG. 21 is a flowchart showing an operation when the mobile host receives a home agent received message.

FIG. 22 is a flowchart showing an operation when the mobile host receives a home agent non-received message.

FIG. 23 is a diagram showing a format of a multicast address used for multicast communication.

FIG. 24 is a diagram showing a specific example of the scope field of FIG. 23;

FIG. 25 is a diagram illustrating an example of a conventional network capable of performing multicast communication of a mobile host.

FIG. 26 is a diagram for explaining a transfer participation method.

FIG. 27 is a diagram for explaining a direct participation method.

[Explanation of symbols]

Reference Signs List 100 backbone network 101, 102, 103, 104 subnetwork 105, 106, 107, 108 router 110, 111, 112, 113 mobile host 120, 121 home agent 251 subnetwork 252 mobile host 253 subnetwork 254 subnetwork 255 foreign agent 256 Location information notification message 257 Home agent 258 Location information notification message 261 Source 262 Multicast packet 263 Scope 264 Home network 265 Home agent 266 Mobile host 267 Bidirectional tunnel 271 Scope 272 Home network 273 Mobile host 274 Source 275 Multicast packet

Continuation of front page (56) References JP-A-10-13910 (JP, A) JP-A-9-326791 (JP, A) JP-A-8-163156 (JP, A) JP-A-6-337824 (JP) JP-A-4-157940 (JP, A) IEICE Technical Report, Vol. 97 No. 353, SSE97-133, Kazuhiro Okanoue, Tomoki Osawa, "Extension of IP Multicast for Mobile Host Support", pages. 43-48 Proceedings of the 1997 IEICE General Conference, Telecommunications 2, B-7-147, Kazuhiro Okanoue, Tomoki Osawa, "IP Multicast Packet Transfer Control Considering Mobile Hosts", IEEE Communications Magazine, Vol. 35 No. 1, January 1997, Xyl omeons, G.W. et al. , "IP Multicast for Mobile Hosts", pages. 54-58 IEEE Infocom '96, The Conference on Computer Communications, Proceedings Volume. 1, March 1996, Acharya, A .; et al. , "IP Multicast for Mobile Internetworking", pages. 67-74 RFC-2002. C Perkins, "IP Mobility Sup port", October. 1996 Processeds Second International Works on Services in Distributed and networked Environments, June 1995, Chikarmane, V.A. et al. , "Mobile IP-based d Multicast as a Service for Mobile Hosts", pages 11-18, RFC-1112. S. Deering, "Host Extensions for IP Multicasting", August. 1989 (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 12/46 H04L 12/56 G06F 13/00 H04L 12/28 INSPEC (DIALOG) JICST file (JOIS)

Claims (23)

(57) [Claims] 1. On a network in which a plurality of sub-networks each connected to a plurality of hosts are interconnected, one of the plurality of hosts serves as a source host, and one or more of the plurality of sub-networks are It is possible to connect to any of the plurality of sub-networks in a multicast communication for selecting a sub-network to form a multicast group and transmitting information to all other hosts connected to the sub-network belonging to the multicast group. A method of joining a mobile host managed by a node called a home agent disposed in any of the plurality of sub-networks, wherein the source host is called group characteristic information.
Predetermined information about a multicast group, i) a group for identifying the multicast group;
Group identifier, and ii) the home agent that received the group characteristic information.
To the mobile host
A transfer enable / disable attribute indicating whether transfer is permitted or not; and iii) the mobile host joins the multicast group.
To participate, the home agent must
Connected to a subnetwork belonging to a multicast group.
Attribute that indicates whether or not it is necessary
If, and notified to the multicast group comprising at which information, b) the home agent, the group characteristic information received, transferred to the mobile host, c) said mobile host, the source host Receiving the group characteristic information transmitted from the home agent or the group characteristic information transferred from the home agent, and determining whether to join the multicast group based on the predetermined information. The multicast communication method of the mobile host. 2. The mobile host, when deciding whether to participate in the multicast group based on the group characteristic information transmitted from the source host,
2. The multicast communication method for a mobile host according to claim 1, wherein an inquiry is made to the home agent, and whether to join the multicast group is determined based on a response message. 3. The home agent checks the transfer propriety attribute included in the received group property information, and if transfer is possible, adds a transfer flag indicating transfer to the group property information, 2. The multicast communication method for a mobile host according to claim 1 , wherein the transfer is performed to the mobile host. 4. The mobile agent, wherein the home agent manages a plurality of mobile hosts, the home agent includes a group characteristic transfer table for registering transfer necessity / unnecessity of the group characteristic information for each group identifier for each mobile host, Of the mobile hosts that have transmitted the transfer unnecessary message, the transfer unnecessary is registered in the group characteristic transfer table corresponding to the group identifier included in the transfer unnecessary message, and the group identifier is registered for the mobile host. 4. The method according to claim 3 , wherein said group characteristic information is not transferred. 5. The transfer host group table for registering: a) a directly joinable group table for registering a group identifier of a multicast group to which the mobile host can directly join; C) having a non-participating group table for registering a group identifier of a non-participating multicast group; and d) upon receiving the group characteristic information, confirming the transfer flag and receiving the group characteristic. E) determining whether the information has been transferred from the home agent; and e) if the group property information has been transferred from the home agent, converting the group property information from the directly joinable group table to the group property information. Retrieving the group identifier contained, f) If not registered, it is determined that transfer participation to join the multicast group is possible via the home agent, and if the group identifier is registered in the non-participation group table, the group identifier is deleted, and the group identifier is deleted. 5. The multicast communication method for a mobile host according to claim 3 , wherein the mobile host is registered in a transfer participation possible group table so as to transfer and participate in the multicast group. 6. The home agent, when the transfer propriety attribute of the received group property information indicates transfer permission, a) the group identifier included in the group property information for the mobile host; Performs an inquiry as to whether or not the mobile host is registered in the directly joinable group table. B) When the response from the mobile host is not registered, the group characteristic information is transferred to the mobile host. 6. The method according to claim 5, wherein
Mobile host multicast communication method. 7. The mobile host, when the received group characteristic information is transferred from the home agent, and when the group identifier is registered in the directly joinable group table, 6. The method according to claim 5 , further comprising transmitting a transfer unnecessary message to the home agent. 8. When the mobile host determines that the received group characteristic information is transmitted directly from the transmission source host, and if the member restriction presence / absence attribute indicates no member restriction, the mobile host directly 7. The multicast communication method for mobile hosts according to claim 5 , wherein the group identifier is registered in a jointable group table to directly join the multicast group. 9. The method according to claim 9, wherein the mobile host determines that the received group characteristic information is transmitted directly from the source host, and the member restriction presence / absence attribute indicates that the member restriction is present. Inquires the home agent, determines whether to participate directly or not in response to the response from the home agent. In the case of direct participation, the group identifier is registered in the directly joinable group table, and participation is disabled. In the case of,
7. The multicast communication method for a mobile host according to claim 5 , wherein the group identifier is registered in a non-participation group table. 10. The mobile agent has a group transfer property table for registering the group identifier, the transfer permission / prohibition attribute, and the member restriction presence / absence attribute included in the received group property information. 10. The multicast communication method for a mobile host according to claim 9 , wherein, in response to the inquiry, whether or not the group identifier is registered is transmitted as a response message. 11. When the mobile host determines that the received group characteristic information is transmitted directly from the source host, the mobile host searches for the group identifier from the directly joinable group table, 10. The mobile host multicast communication method according to claim 8, wherein a judgment is made of the attribute of presence or absence of a member restriction when not registered. 12. The mobile host is provided with a logical identifier for identifying the mobile host, which does not depend on the location of the mobile host, and a location identifier depending on a currently connected subnetwork. The method according to claim 1, wherein the home agent manages the mobile host using a location identifier. 13. The multicast communication method for a mobile host according to claim 1, wherein said mobile host can move between said sub-networks while performing communication. 14. A computer system comprising: a plurality of sub-networks connected to each other; and a plurality of hosts connected to the plurality of sub-networks. A multicast communication system capable of selecting one or more sub-networks from among the sub-networks to form a multicast group and transmitting information to all other hosts connected to the sub-network belonging to the multicast group A) a mobile host connectable to any of the plurality of sub-networks; and b) a node called a home agent arranged in any of the plurality of sub-networks and managing the mobile host. C) ) The multicast group is assigned to each of the plurality of hosts. When forming a group, it is called group characteristic information.
Information about the multicast group
I, i) glue for identifying the multicast group
Group identifier, and ii) the home agent that received the group characteristic information.
To the mobile host
A transfer enable / disable attribute indicating whether transfer is permitted or not; and iii) the mobile host joins the multicast group.
To participate, the home agent must
Connected to a subnetwork belonging to a multicast group.
Attribute that indicates whether or not it is necessary
And b) a notifying unit for notifying the multicast group of information including : d) a transferring unit for transferring the received group characteristic information to the home agent to the mobile host; The mobile host receives the group characteristic information transmitted from the source host or the group characteristic information transferred from the home agent, and based on the predetermined information, decides whether to join the multicast group. A multicast communication system comprising a participation permission / inhibition determining means for determining permission / inhibition. 15. The method according to claim 15, wherein the home agent has a group property table for registering the group identifier, the transfer permission / prohibition attribute, and the member restriction presence / absence attribute included in the received group property information. The multicast communication system according to claim 14 , wherein: 16. The transfer means includes a transfer permission / prohibition attribute confirming means for confirming the transfer permission / prohibition attribute included in the received group property information, and if the transfer is permitted, the transfer indicating the transfer to the group property information. by adding a flag, it is characterized in that so as to transfer to the mobile host according to claim
14 or 15 multicast communication systems. 17. The multicast communication system according to claim 16 , wherein said transfer means has an inquiry means for inquiring of said mobile host whether said group characteristic information to be transferred has already been received by said mobile host. . 18. The home agent manages a plurality of mobile hosts, and has a group property transfer table for registering transfer necessity / unnecessity of the group property information for each mobile host for each group identifier. 18. The multicast communication system according to claim 16 , wherein the means transfers the group characteristic information only to mobile hosts registered as necessary in the group characteristic transfer table. 19. The mobile host has means for detecting the transfer flag, and distinguishes whether the received group characteristic information is transmitted from the source host or transferred from the home agent. 17. The multicast communication system according to claim 16 , wherein the multicast communication is performed. 20. The mobile host, wherein the member restriction presence / absence attribute means for determining the member restriction presence / absence attribute, and when the member restriction presence / absence attribute means determines that there is a member restriction, the mobile agent determines whether the home agent is a member. 20. The multicast communication system according to claim 19 , further comprising inquiry means for making an inquiry. 21. The mobile host, comprising: a) a directly joinable group table for registering a group identifier of a multicast group which can directly participate; and b) a transfer joinable group table for registering a group identifier of a multicast group which can be transferred. The multicast communication system according to claim 14 , further comprising: c) a non-participation group table for registering a group identifier of a non-participating multicast group. 22. The mobile host, when receiving the group characteristic information transferred from the home agent, first searching means for searching whether the group identifier is registered in the directly joinable group table, A transfer-unnecessary message transmitting unit that transmits a transfer-unnecessary message to the home agent when the first search unit detects that the group identifier is registered in the directly joinable group table; If the search means detects that the group identifier is not registered in the directly joinable group table, the search means searches whether the group identifier is registered in the unjoinable group table and, if the group identifier is registered, the group A second search means for deleting the identifier; 22. A registration unit for registering the group identifier in the transfer participation possible group table when the search unit detects that the group identifier is not registered in the directly joinable group table. Multicast communication system. 23. The mobile host, when receiving the group characteristic information directly from the source host, a first search means for searching whether the group identifier is registered in the directly joinable group table, When the first search means detects that the group identifier is not registered in the directly joinable group table,
A second search unit for searching whether the group identifier is registered in the non-participating group table; and a second searching unit that detects that the group identifier is not registered in the non-participating group table. A member restriction judging unit for judging the attribute of the member restriction, and an inquiry unit for inquiring the home agent whether the member is a member when the member restriction judging unit judges that the member restriction is present, When the means determines that there is no member restriction, and when a response indicating that the user is a member is obtained in response to the inquiry of the inquiry means, the first search means sets the group identifier to the group that can be directly joined. Register in the table and respond to the inquiry by the inquiry means 22. The multicast communication system according to claim 21 , wherein the second search means registers the group identifier in the non-participating group table when a response indicating that the request is not received is obtained.